Heat exchangers are commonly utilized to promote heat transfer from a first fluid (herein, a “temperature-regulated fluid”) to a second fluid (herein, a “heat-receiving medium”). Depending upon design, heat exchangers often contain multiple elongated, thin-walled HX tubes through which the temperature-regulated fluid is circulated during heat exchanger operation. Such heat exchangers are referred to herein as “tube-containing heat exchangers” and include radiators, shell-and-tube heat exchangers, double pipe heat exchangers, and others. As the temperature-regulated fluid flows through the HX tubes, heat is transferred from the temperature-regulated fluid to the HX tubes, thermally conducted through the tube walls, and ultimately transferred to a heat-receiving medium in contact with the tube exteriors. The heat-receiving medium may be ambient gasses when the heat exchanger assumes the form of a radiator, in which case heat removal may be promoted by impinging airflow against the tube exteriors. Alternatively, in the case of a shell-and-tube heat exchanger, heat extracted from the temperature-regulated fluid may be transferred to the heat-receiving medium in the form of a second fluid (liquid or gas) circulated through the heat exchanger.
In a tube-containing heat exchanger, the physical characteristics of the HX tubes may be impactful on the thermal performance, size, weight, shape, and temperature tolerances of the heat exchanger. HX tube thickness and composition, in particular, may be at least partially determinative of the overall weight and thermal performance characteristics of the heat exchanger, particularly when containing a relatively large number of elongated HX tubes. When deployed onboard an aircraft or other vehicle, the HX tubes are ideally composed of a material possessing a relatively high thermal conductivity to maximize thermal transfer, while further having a relatively low density to minimize weight. Lightweight, Al-based alloys are often selected for HX tube fabrication for these reasons. As conventionally formulated and fabricated, however, HX tubes composed of Al-based materials remain undesirably heavy for airborne usage and other specialized applications. Moreover, the thermal tolerances of Al-based HX tubes can be undesirably limiting in at least some instances; e.g., conventional Al-based HX tubes may be unsuitable for prolonged exposure to temperatures approaching or exceeding 350° C., as may be unduly restrictive in certain high temperature applications.
There thus exists an ongoing demand in the aerospace industry and elsewhere for the development of high performance, tube-containing heat exchangers having enhanced temperature tolerances, lightweight constructions, and other desirable physical characteristics, such as enhanced oxidation and corrosion resistance. Ideally, embodiments of such tube-containing heat exchangers, and particularly the HX tubes contained therein, would be amenable to fabrication utilizing relatively low cost, efficient manufacturing processes affording a high level of flexibility in heat exchanger design. Other desirable features and characteristics of embodiments of the present invention will become apparent from the subsequent Detailed Description and the appended Claims, taken in conjunction with the accompanying drawings and the foregoing Background.